Republican politicians as disparate as Jeb Bush and Rand Paul have long decried Donald Trump as a fake conservative, who doesn’t truly believe in the movement’s first principles. National Review recently published an entire issue “Against Trump,” making the same argument.

They’re all wrong. Trump is the only true conservative running for the Republican nomination, outside of long shot Rick Santorum.

Since the Democratic Party abandoned classical liberalism for progressivism at the turn of the 20th century, the classical liberal ideas of laissez faire free markets, personal liberty and a noninterventionist foreign policy have needed a new home. Due to the outright hostility towards them in the progressive-liberal movement, they’ve largely resided within the conservative movement.

This is a very unnatural marriage between worldviews that are for the most part antithetical to each other. American history during the 19th century was very much a war between classical liberal and conservative ideas, with the former dominating the first half of the century and the latter the second half. But after Woodrow Wilson, classical liberalism had nowhere else to go. As a result, classical liberal ideas have become jumbled together with classical conservative ones.

For example, the natural consistency in supporting a laissez faire (i.e., “noninterventionist”) economy and a noninterventionist foreign policy has disappeared. Today, one finds rabid supporters of free markets also supporting a highly interventionist foreign policy. They’ve selected positions they like without understanding the philosophical basis for either, resulting in a confused, self-contradictory worldview.

This is why so many on the right have decried Trump as an inauthentic conservative. They don’t understand the difference between the classic conservative worldview that informs Trump’s positions and the classical liberal worldview that has found a dubious home within the conservative movement. In an attempt to sort this out, here are five reasons Trump is, indeed, an authentic conservative:

He’s a protectionist. British and American Conservatives from Edmund Burke (outside the British Empire) to Alexander Hamilton to Abraham Lincoln to Herbert Hoover to George W. Bush have all been protectionists. It’s the natural economic expression of their worldview.

He’s a nationalist. Conservatism can be split between Hobbesian centralizers and Burkean constitutionalists. Trump is a classic example of the former, placing “national greatness,” as fellow conservative centralizer Alexander Hamilton put it, above the rights of the individual. That all rights, including liberty and property, are revocable by the sovereign power in the interests of preserving the commonwealth are inherent conservative principles. Trump’s enthusiastic support for eminent domain is just one example.

He’s a militarist. Trump has expressed skepticism about the Iraq War (it turns out he only opposed it a year after the invasion), but he’s also said the U.S. should invade Iran and take their oil. Like all conservatives in British and American history, he believes only a worldwide military empire can ensure the “greatness” he wants to restore to the nation.

He’s a nativist. Distrust of foreigners is another foundational conservative principle. Conservatives believe any disruption of longstanding traditions is a threat to all of society. Immigrants naturally bring with them different perspectives, worldviews and skill sets. They not only represent competition for domestic employment (see #1), but threaten to introduce new sensibilities to the population, which is a threat to societal order.

He’s a Police Stater. Trump’s suggestions to “shut down parts of the internet” and his denigration of freedom of speech are classic conservative tendencies. Conservatives have always promoted unlimited power for law enforcement. That’s because they see law enforcement as the only thing that stands between a peaceful society and the “war of everyone against everyone” Hobbes asserted was man’s natural state. The Patriot Act, Military Commissions Act of 2006 and Trump’s ideas about the internet are all classic conservative responses to perceived threats.

Trump is horrifying those on the right and the left because he represents a return to pure conservatism. Ironically, what attracts most everyday people to the conservative movement isn’t true conservatism at all. It’s the classical liberal ideas tenuously residing within conservatism which more naturally belong to today’s libertarians.

I’ve tried to sort all of this out in my latest book. You can read a free excerpt here.